stoning the hammer cocking surface and underside/cocking surface of the carrier may alleviate your problems. smoothing things up a bit and greasing those surfaces will allow your ak to run more smoothly.

also, check the alignment of your gas piston with the gas tube remove. sometimes the drag is actually caused by the piston, and the hammer hangupo point is the result of that friction (it is normal for the hammer to slow the carrier down, as the cocking surface must overdrive the hammer travel in order to cock the rifle).